Composition influence on positron annihilation parameters in ZnO‐based nanocrystal semiconductor powders

Abstract

Zn 1-x Mg x O powders at various compositions were obtained by mechanical milling from the binary oxides. The progressive incorporation of Mg atoms into the ZnO lattice was monitored by X-ray diffraction (XRD). The evolution of annihilation parameters with milling time and composition were analyzed and related to the possible types of mechanical and substitutional induced defect present. It was concluded that the average lifetime constitute a useful parameter to sense the complete cation substitution in the wurtzite structure.

Trivalent dopants on ZnO semiconductor obtained by mechanical milling

“…4 shows the resulting average lifetimes for Al-doped ZnO together with results for other ZnO-doped samples for comparison. In previous works [18,24] we have concluded that this parameter was able to sense the cation incorporation into the ZnO structure. When cation substitution is achieved the average lifetime approximates the value of undoped ZnO (full start in Fig.…”

“…Details of this technique can be found elsewhere [23,24]. These observed lifetimes take into account positron annihilation in the bulk of the material and the presence of different point defects as well.…”

Dopants incorporation in ZnO mechanical milled powders sensed by positrons

“…In a previous work we prepared ternary oxides Zn 1−x M x O (M: Cd, Mg) using a planetary ball milling without getting a complete mixture of the starting oxides [3]. Under different experimental conditions Mg substitution in ZnO was afterwards successfully obtained [4]. This time we present a structural study on mechanical milled M-doped ZnO (M: Cd, Mg) powders by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and positron lifetime annihilation spectroscopy (PALS).…”